Siloxane grafted vinyl polymers and their use in hydrosilylation reactions are known in the art. For example, copolymers of a radical-polymerizable monomer, such as a methyl methacrylate, and a polysiloxane having a degree of polymerization between 25 and 500 containing an alkenyl group on one molecular terminal and a radical-polymerizable group on the other molecular terminal are disclosed in Japanese Laid-Open Patent Application [Kokai] Hei 1-252,616. However, the content of the alkenyl groups in these vinyl polymers exerts its influence on the degree of polymerization of the polysiloxane and on the content of siloxane. In particular, an increase in the degree of polymerization in the siloxane chain decreases the content of the alkenyl groups. Therefore, even though the curing reaction results in some cross-linking from the use alkenyl groups, the composition is not sufficiently cured and thus not suitable as coating films. When the vinyl polymer is produced with radical-polymerizable monomers such as acrylic acid esters, copolymerization often results in gelation.